The response of calcareous nannoplankton to the latest Pliensbachian-early Toarcian environmental changes in the Camino section (Basque Cantabrian Basin, North Spain)

2021 ◽  
pp. SP514-2020-256
Author(s):  
Ángela Fraguas ◽  
Juan José Gómez ◽  
Antonio Goy ◽  
María José Comas-Rengifo
Keyword(s):  
Environmental Changes ◽  
Principal Component ◽  
Black Shales ◽  
Time Interval ◽  
Calcareous Nannofossils ◽  
Calcareous Nannofossil ◽  
Content Type ◽  
Lowermost Part ◽  
Supplementary Material ◽  
Basque Cantabrian Basin

AbstractQuantitative analysis performed on latest Pliensbachian-early Toarcian calcareous nannofossil assemblages from the Camino section (Basque Cantabrian Basin), allowed to decipher their response to the environmental changes recorded during this time interval, characterized by an extinction event. The results were introduced within a principal component analysis and compared to the stable isotope and total organic carbon curves. During the latest Pliensbachian, the Mirabile and the lowermost part of the Semicelatum Ammonite Subzones, Schizosphaerella, Bussonius prinsii, Biscutum finchii, Calcivascularis jansae and Similiscutum avitum, taxa that probably thrived in rather cold waters, dominated the calcareous nannofossil assemblages. Coinciding with the warmer and probably wetter conditions, which probably led to an increase in surface water fertility, recorded slightly below the extinction boundary, the mesotrophic taxa B. novum, L. hauffii and Calyculus spp. were dominant. Nevertheless, T. patulus and C. jansae, which became extinct just below the extinction boundary, show preferences for oligotrophic conditions. Salinities similar to those of modern oceans have been inferred around the extinction boundary, considering the coupling between the abundances of Calyculus spp. and the species richness, and the absence of black-shales. After the extinction boundary, nannofossil assemblages were dominated by the deep-dweller C. crassus and the shallow-dweller Lotharingius species, interpreted as opportunistic taxa. This work confirms that calcareous nannofossils are a useful tool for palaeoceanographic and palaeoenvironmental reconstructions, especially in terms of climatic changes.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5481527

Molecular and petrographical evidence for lacustrine environmental and biotic change in the palaeo-Sichuan mega-lake (China) during the Toarcian Oceanic Anoxic Event

2021 ◽  
pp. SP514-2021-2
Author(s):  
Weimu Xu ◽  
Johan W. H. Weijers ◽  
Micha Ruhl ◽  
Erdem F. Idiz ◽  
Hugh C. Jenkyns ◽  
...  
Keyword(s):  
Organic Matter ◽  
Sichuan Basin ◽  
Large Scale ◽  
Algal Growth ◽  
Black Shales ◽  
Content Type ◽  
Oceanic Anoxic Event ◽  
Anoxic Event ◽  
Supplementary Material ◽  
The Sichuan Basin

AbstractThe organic-rich upper Lower Jurassic Da'anzhai Member (Ziliujing Formation) of the Sichuan Basin, China is the first stratigraphically well-constrained lacustrine succession associated with the Toarcian Oceanic Anoxic Event (T-OAE; ∼183 Ma). The formation and/or expansion of the Sichuan mega-lake, likely one of the most extensive fresh-water systems to have existed on the planet, is marked by large-scale lacustrine organic productivity and carbon burial during the T-OAE, possibly due to intensified hydrological cycling and nutrient supply. New molecular biomarker and organic petrographical analyses, combined with bulk organic and inorganic geochemical and palynological data, are presented here, providing insight into aquatic productivity, land-plant biodiversity, and terrestrial ecosystem evolution in continental interiors during the T-OAE. We show that lacustrine algal growth during the T-OAE accounted for a significant organic-matter flux to the lakebed in the palaeo-Sichuan mega-lake. Lacustrine water-column stratification during the T-OAE facilitated the formation of dysoxic-anoxic conditions at the lake bottom, favouring organic-matter preservation and carbon sequestration into organic-rich black shales in the Sichuan Basin. We attribute the palaeo-Sichuan mega-lake expansion to enhanced hydrological cycling in a more vigorous monsoonal climate in the hinterland during the T-OAE greenhouse.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5433544

Using analytic hierarchy process (AHP)-based index and geographic information system (GIS) in geochemical exploration of gold

2021 ◽  
pp. geochem2021-013
Author(s):  
Erkan Yılmazer ◽  
Murat Kavurmaci ◽  
Sercan Bozan
Keyword(s):  
Hierarchical Structure ◽  
Principal Component ◽  
Content Type ◽  
Distribution Maps ◽  
Rock Samples ◽  
High Sulfidation ◽  
The Hierarchical Structure ◽  
Supplementary Material ◽  
Comparison Of The Results ◽  
Hierarchy Process

In this study, a gold exploration index (GEI) that reduces financial expenditures and time losses during exploration studies has been developed using the Analytical Hierarchy Process (AHP) in a region where a high sulfidation epithermal Au deposit exists. The GEI can be used to predict the location of the target element by evaluating the maps obtained from related element distributions together with a GEI-based prediction map. The hierarchical structure of the index has been established based on geochemistry of the rock samples. The elements used in the design of the hierarchical structure are arsenic (As), silver (Ag), antimony (Sb), copper (Cu), manganese (Mn), lead (Pb) and zinc (Zn), which are determined by the correlation analysis and experts’ opinions. The efficiency scores of the alternatives were converted into prediction maps called GEI-based anomaly distribution maps. They were compared with the maps derived from both GIS-based overlay analysis of the rock samples and spatial gold distribution. The efficiency scores of the alternatives in these maps were categorized into three groups as "high,” "medium," and "weak" in terms of gold potential. Comparison of the results with those derived using Principal Component (PCA), Weighted Total (WS) and Weighted Product Models (WPM) methods showed that the produced index yields reliable information that can be used to determine where gold enrichment occurs, especially in high sulfidation epithermal environments.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5443218

scholarly journals Eocene to Oligocene nannofossils stratigraphy and environmental conditions in Izeh Province, Zagros Basin, East Tethys

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Saeedeh Senemari ◽  
Farah Jalili
Keyword(s):  
Environmental Changes ◽  
Late Eocene ◽  
Marine Phytoplankton ◽  
Asmari Formation ◽  
Calcareous Nannofossils ◽  
Calcareous Nannofossil ◽  
Southwestern Iran ◽  
Pabdeh Formation ◽  
First Time ◽  
Palaeoenvironmental Conditions

AbstractData obtained from the calcareous nannofossils, distributed in the upper part of the Pabdeh Formation (Priabonian–Rupelian) and the lower part of the Asmari Formation (Chattian) in the Bid-Zard section, were used to investigate the Eocene to Oligocene palaeoenvironmental conditions in the southwest of Izeh, southwestern Iran (eastern Tethys). The upper part of the Pabdeh Formation was composed of shale, thin-bedded pelagic limestone and dolostone, which is disconformably overlain by the Asmari Formation. For the first time, 29 species of calcareous nannofossils belonging to 13 genera were identified in the studied section. The calcareous nannofossils in the upper part of the Pabdeh Formation indicate the Isthmolithus recurvus Zone/Sphenolithus pseudoradians Zone (combined zone), Ericsonia subdisticha Zone, Helicosphaera reticulata Zone and Sphenolithus praedistentus Zone, from the Priabonian to the Rupelian. The Sphenolithus ciperoensis Zone of the Chattian was identified in the lower part of the Asmari Formation. Calcareous nannofossil stratigraphy across the upper Eocene–Oligocene interval also reveals a disconformity at the Rupelian/Chattian transition due to a bio-event. Shallowing of the basin and environmental changes in this part of the Tethyan domain could have led to the lithostratigraphic and biostratigraphic changes. In fact, during the late Eocene to late Oligocene, marine phytoplankton was sensitive to climate changes such as decreasing temperature, as well as possibly to a nutrient increase and changes in basin depth.

scholarly journals Tellus regional stream water geochemistry: environmental and mineral exploration applications

2022 ◽  
Vol 22 (1) ◽  
pp. geochem2021-050
Author(s):  
Vincent Gallagher ◽  
Eric C. Grunsky ◽  
Mairéad M. Fitzsimons ◽  
Margaret A. Browne ◽  
Sophie Lilburn ◽  
...  
Keyword(s):  
Stream Water ◽  
Mineral Exploration ◽  
Principal Component ◽  
Water Hardness ◽  
Environmental Issues ◽  
Survey Area ◽  
Background Concentrations ◽  
Water Geochemistry ◽  
Content Type ◽  
Supplementary Material

Regional stream water geochemistry acquired as part of the Tellus programme in Ireland has been analysed to assess its potential for application to environmental assessment and mineral exploration. Interpolated geochemical maps and multivariate statistical analysis, including principal component analysis and random forest classification, demonstrate broad geogenic control of stream water chemistry, with both bedrock and subsoil contributing to the patterns observed. Surface water regulations set Environmental Quality Standard values for individual Priority Substances and Specific Pollutants that may depend on background concentrations and/or water hardness. The high resolution of Tellus stream water data and their location on low-order streams have allowed estimation of background concentrations and water hardness in the survey area, with significant implications for water monitoring programmes. Anthropogenic inputs to stream water in the survey area come mainly from agricultural sources and Tellus data suggest few catchments are unaffected. Comparison of Tellus stream water geochemistry with stream sediment and topsoil geochemistry suggest that stream water geochemistry has strong potential for use in mineral exploration, with the same base metal and gold pathfinder anomalies apparent in all three data sets. Cluster analysis indicates that base metals in stream water are associated with organic matter but statistical analysis may be employed to distinguish mineralization-related signatures.Supplementary material: Comparison of cation/anion associations using Piper plots and principal component analysis is available at https://doi.org/10.6084/m9.figshare.c.5683094Thematic collection: This article is part of the Hydrochemistry related to exploration and environmental issues collection available at: https://www.lyellcollection.org/cc/hydrochemistry-related-to-exploration-and-environmental-issues

Spatial heterogeneity of redox-sensitive trace metal enrichments in upper Ediacaran anoxic black shales

2021 ◽  
pp. jgs2020-234
Author(s):  
Chengsheng Jin ◽  
Chao Li ◽  
Thomas J. Algeo ◽  
Guochang Wang ◽  
Wei Shi ◽  
...  
Keyword(s):  
Spatial Heterogeneity ◽  
Water Mass ◽  
Significant Degree ◽  
Black Shales ◽  
Redox Conditions ◽  
Cambrian Explosion ◽  
Content Type ◽  
Oxygen Levels ◽  
Link Type ◽  
Supplementary Material

The Ediacaran radiation of metazoans is widely thought to have been triggered by an increase in atmospheric and oceanic oxygen levels. Although supported by other proxies, rising oxygen levels were deduced to a significant degree from sedimentary enrichments of redox-sensitive trace elements (RSTEs). However, some organic-rich shales of this period show only minor enrichments in RSTEs, leaving the significance of RSTE data for palaeo-oxygenation interpretations in doubt. We measured and compiled proxies for marine redox conditions (Fe species, RSTEs), total organic carbon (TOC) and water mass restriction (Mo/TOC and Co × Mn v. Cd/Mo) in the intra-shelf Jiulongwan and basinal Sandu sections of the Nanhua Basin in South China. Compared with the same proxies from coeval sections in the Nanhua Basin and globally, our results document a strong spatial heterogeneity of RSTE enrichments in anoxic black shales during the late Ediacaran. We infer that RSTE enrichments were strongly influenced by local factors, such as basinal restriction, seawater RSTE concentrations, and differential elemental responses to redox conditions and other influences. The broader significance of our findings is that they highlight the difficulty of investigating global redox conditions based on an analysis of local RSTE proxies within a single depositional basin or a limited number of study sections.Thematic collection: This article is part of the Advances in the Cambrian Explosion collection available at: https://www.lyellcollection.org/cc/advances-cambrian-explosionSupplementary material: Tables S1–S3 are available at https://doi.org/10.6084/m9.figshare.c.5325047

scholarly journals UPPER BURDIGALIAN-MIDDLE SARMATIAN CALCAREOUS NANNOFOSSILS FROM TOTEA-VĂLENI AREA (GETIC DEPRESSION, ROMANIA)

2021 ◽  
pp. 75-82
Author(s):  
Daniela Ghiță ◽  
Vasile Șindilar
Keyword(s):  
Time Interval ◽  
Calcareous Nannofossils ◽  
Calcareous Nannofossil ◽  
Palaeoenvironmental Reconstructions ◽  
Western Side

This work presents the calcareous nannofossils identified in samples recovered from 7 boreholes drilled on the western side of the Olt River, in the Totea, Colibasi, Radinesti and Valeni areas, within the central-southern part of the Getic Depression. These boreholes crossed upper Burdigalian–middle Sarmatian sediments. The identified assemblages are typical for the following calcareous nannofossil biozones: upper part of NN 3 – lower part of NN 4, corresponding to the late Burdigalian time interval, upper part of NN 4, corresponding to the early Badenian, NN 5, spanning the middle Badenian, and, respectively, NN 6-NN 8, covering the late Badenian – middle Sarmatian interval. The diversity and abundance of the identified nannofossil assemblages allow palaeoenvironmental reconstructions

scholarly journals The Eocene−Oligocene Transition in Nanggulan, Java: lithostratigraphy, biostratigraphy and foraminiferal stable isotopes

2021 ◽  
pp. jgs2021-006
Author(s):  
Helen K. Coxall ◽  
Tom Dunkley Jones ◽  
Amy P. Jones ◽  
Peter Lunt ◽  
Ian MacMillan ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Planktonic Foraminifera ◽  
Warm Pool ◽  
Time Interval ◽  
Content Type ◽  
Continental Scale ◽  
Central Java ◽  
South Central ◽  
Sunda Arc ◽  
Supplementary Material

The Nanggulan section in south central Java comprises open marine sediments and volcanic deposits of Eocene-Oligocene age that accumulated in a marginal basin within the young Sunda Arc complex. A new borehole captures the stratigraphy and showcases the exceptional preservation of calcareous microfossils across an apparently complete Eocene-Oligocene Transition (EOT), a time interval significant for the initiation of continental scale glaciation on Antarctica. Low-resolution benthic and planktonic foraminifera oxygen and carbon stable isotopes (δ18O and δ13C) record increasing δ18O and δ13C in the basal Oligocene, allowing correlation to global records. Isotopic values imply warm temperatures and relatively high nutrients along the SE Java margin. The Nanggulan EOT is a valuable archive for reconstructing ocean-climate behavior and plankton evolution and extinction in the Indo-Pacific warm pool. The borehole also adds to understanding of the early stages of Sunda Arc volcanism.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5429453

scholarly journals Current understanding on the Cambrian Explosion: questions and answers

PalZ ◽  
2021 ◽  
Author(s):  
Xingliang Zhang ◽  
Degan Shu
Keyword(s):  
Environmental Changes ◽  
Size Variation ◽  
Progressive Increase ◽  
Cambrian Explosion ◽  
Time Interval ◽  
Early Cambrian ◽  
Ecological Processes ◽  
Questions And Answers ◽  
Evolutionary Event ◽  
History Of

AbstractThe Cambrian Explosion by nature is a three-phased explosion of animal body plans alongside episodic biomineralization, pulsed change of generic diversity, body size variation, and progressive increase of ecosystem complexity. The Cambrian was a time of crown groups nested by numbers of stem groups with a high-rank taxonomy of Linnaean system (classes and above). Some stem groups temporarily succeeded while others were ephemeral and underrepresented by few taxa. The high number of stem groups in the early history of animals is a major reason for morphological gaps across phyla that we see today. Most phylum-level clades achieved their maximal disparity (or morphological breadth) during the time interval close to their first appearance in the fossil record during the early Cambrian, whereas others, principally arthropods and chordates, exhibit a progressive exploration of morphospace in subsequent Phanerozoic. The overall envelope of metazoan morphospace occupation was already broad in the early Cambrian though it did not reach maximal disparity nor has diminished significantly as a consequence of extinction since the Cambrian. Intrinsic and extrinsic causes were extensively discussed but they are merely prerequisites for the Cambrian Explosion. Without the molecular evolution, there could be no Cambrian Explosion. However, the developmental system is alone insufficient to explain Cambrian Explosion. Time-equivalent environmental changes were often considered as extrinsic causes, but the time coincidence is also insufficient to establish causality. Like any other evolutionary event, it is the ecology that make the Cambrian Explosion possible though ecological processes failed to cause a burst of new body plans in the subsequent evolutionary radiations. The Cambrian Explosion is a polythetic event in natural history and manifested in many aspects. No simple, single cause can explain the entire phenomenon.

Robust-PCA-based hierarchical plane extraction for application to geometric 3D indoor mapping

2014 ◽  
Vol 41 (2) ◽  
pp. 203-212 ◽  
Author(s):  
Suyong Yeon ◽  
ChangHyun Jun ◽  
Hyunga Choi ◽  
Jaehyeon Kang ◽  
Youngmok Yun ◽  
...  
Keyword(s):  
Principal Component ◽  
Point Clouds ◽  
Previous Method ◽  
Divide And Conquer ◽  
Sensor Data ◽  
Estimation Accuracy ◽  
Content Type ◽  
Extraction Algorithm ◽  
Plane Extraction ◽  
Scan Data

Purpose – The authors aim to propose a novel plane extraction algorithm for geometric 3D indoor mapping with range scan data. Design/methodology/approach – The proposed method utilizes a divide-and-conquer step to efficiently handle huge amounts of point clouds not in a whole group, but in forms of separate sub-groups with similar plane parameters. This method adopts robust principal component analysis to enhance estimation accuracy. Findings – Experimental results verify that the method not only shows enhanced performance in the plane extraction, but also broadens the domain of interest of the plane registration to an information-poor environment (such as simple indoor corridors), while the previous method only adequately works in an information-rich environment (such as a space with many features). Originality/value – The proposed algorithm has three advantages over the current state-of-the-art method in that it is fast, utilizes more inlier sensor data that does not become contaminated by severe sensor noise and extracts more accurate plane parameters.

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